1. Field of the Invention
The present invention relates to poppet valves for internal combustion engines, and more particularly to a system for permitting a poppet valve to rotate during engine operation.
2. Background of the Invention
It is well known that rotation of a poppet valve in use will increase the life of the valve since the same area of the valve is not continuously presented to the combustion gases. Warping is reduced and carbon deposit is not as likely to take place on the valve seats or faces. With some conventional valve retainers, the valve springs have been attached to prevent rotation. Others that permit rotation can permit the keepers to come loose from the valve stem resulting in loss of the valve. Attempts have been made in the prior art to provide a rotatable poppet valve. For example, Douglas et al, U.S. Pat. No. 2,165,239 shows a design in which the valve is free to rotate. A cage for a set of ball bearings which rides on a race formed in the valve stem is taught by Aiken, U.S. Pat. No. 2,841,128. Although the Aiken design permits the valve to rotate, it requires that a precision race be provided on each valve stem which can add greatly to the cost of the valve and also presents a weak point in the valve stem.
Thus, there is a need for a simple, low cost system for poppet valves which will permit the valve to rotate during operation and which will overcome the disadvantages of the prior art attempts to solve this problem.